Cranky Contraption Exploration

I have become somewhat obsessed with the concept of automata over the past month or so. I have seen multiple iterations of cardboard automata. The Tinkering Studio has a FANTASTIC pdf which explains the basics as well as facilitation tips for educators. I had this on my agenda to work into my makerspace this year, but it was when I saw this video that my imagination was set on fire:

I started exploring how others had been using them and I was hooked. This video shows one of the workshops that the Tinkering Studio offered to local educators and shows how it is much easier to focus on the mechanisms since the ‘enclosure’ is essentially pre-made in the form of the wood block.

When I saw @MicheleGuieu ‘s collection of cranky contraptions her third-grade students made, I knew I needed to figure out how to work this into my makerspace’s plan for the spring.

Enjoy 30 seconds of fun Cranky Contraptions made by the 3rd graders at Village Elementary School! Making something is also an opportunity to think about #nature, the role humans play in climate change, ressources/sustainability, & pollution #STEAM#SFbay Thanks @TinkeringStudio! pic.twitter.com/nB2jYuB82k

I started by trying to make as many of the models as I could from the Tinkering Studio’s video. As our school is in the process of raising Rainbow Trout through the Trout in the Classroom Project, I decided to make a trout chasing its dinner!

Digging In For a Challenge

One of my dear friends retired this past spring. Each year she and I would talk about the Sandhill Cranes as they migrate back to our area. She has a pair that has come back to her yard every year and she has ‘named’ them Fred and Ethel.

I wanted to honor her by creating a Sandhill Crane cranky contraption.

A photo of two Sandhill Cranes I snapped while on a hike one spring.

Next, I explored the different mechanisms that could be used to make a bird’s wings ‘flap.’

This would take some tweaking – but using scrap plastic for clear wing attachments is a nice touch https://t.co/F1gPGzxH7i

I couldn’t find one that would keep the body of the bird in place while allowing the wings to flap. I decided to explore how ornithopters accomplished this. I downloaded several ornithopter plans and studied their ‘crank’ mechanisms. It was pretty easy to get the movement of one wing. It was a bit more complicated when adding the ‘other wing.’ The addition of the second strut causes an asymmetrical movement. Thankfully, the awesome ornithopter site shows how to create an offset crank that will allow the second strut to move in a way that causes a symmetrical movement.

I started tinkering with the mechanism on my model. It was very difficult to ‘pre-bend’ the crank. I found that I had to place the wire through the block and thenbend it. I used what I had on hand for my wooden pieces, chopsticks! They worked out well as they had a flat edge at the base and a smooth, round portion at the other end. The flat edge made it easy for drilling. It took me several tries to find the right ‘length’ for each of the bends.

Experimenting with an ornithopter-like mechanism to create a flapping motion for my Sandhill Crane #crankycontraption You can see the various holes I made in the spars; this helped me determine each of the crank’s bends. It was tough because the wire had to be bent as I went. pic.twitter.com/qdxyM82a1a

Now that I had a semi-working mechanism, I needed to build my Crane. I found a beautiful paper model on Pinterest that I printed out on tabloid-size paper.

I used my paper model on my mechanism to see how I might need to ‘adapt’ the spars that would attach to the wings. This became another pretty big challenge. I wanted the body of the crane to remain in position while the wings moved gently up and down.

I ended up shortening the spars and adding a second joint that was angled down. This corresponded to the movement I was hoping to create better than the straight up and down movement of the original spars. This required a few adaptations to the original ‘wing.’

I used the end of a chopstick on an angle to ‘slide’ through a pocket to cause an even up and down movement.

I traced the paper pattern onto foam and cut and folded it. I needed something to give the crane rigidity so I reached again for my chopsticks! I glued one in the middle of the fold and used two others to place the crane at the right height. It took several iterations of cranks and wing spars. I needed to create a ‘pocket’ that the spar would slide in to get the wings to move the way I had intended.

You can see the small pocket I created to allow the wing spar to move smoothly.

I also had to change the crank several times. Wire breaks after being bent over and over again. I had to re-bend the crank and ended up using an unbent large paper clip as my wire. I had drilled several holes in the second wing crank. This allowed me to adjust the bends in the crank in small ways until I found an equal up and down movement of both wings.

You can see the holes in the left-wing spar. I had to adjust the height as I went.

After lots and lots of experimentation, I had a fairly successful moving model.

Take Aways

The biggest take away from this project was that getting the wings to ‘flap’ was a lot harder than I imagined. It ended up taking two afternoons of solid work. I enjoyed working through each of the problems as they came up. There were a few times I thought I might just abandon it, but I’m glad I persisted. It feels great to have successfully created what I imagined!

Moving Forward:

I would like to make an ornithopter using the same type of crank mechanism I created for this model.

I am also going to construct each of the models the Tinkering Studio showed in their video. I think having these available for the students to manipulate might encourage them to go ‘beyond’ the simple up and down model. I can’t wait to see what the students create!